A variety of surgical procedures and medical conditions require the use of a carefully regulated fluid vacuum system. For example, draining a patient's chest cavity of accumulated fluid and maintaining a partial vacuum in the patient's chest cavity to permit the lungs to function is sometimes required incident to certain chest surgery procedures. Also, it may be necessary to drain a patient's chest cavity of accumulated fluid and to evacuate the chest cavity incident to accidental puncturing of the chest wall, to ensure that the lungs will function properly.
Several types of prior art drainage systems have been used for this purpose. For example, one type of system uses gravity to effect drainage of the fluids from the chest cavity. In this type of system, a bottle is placed below the level of the patient's chest. The bottle is closed at its top by a rubber stopper through which a first end of a drainage tube is inserted. The second end of the drainage tube is attached to a catheter inserted into the patient's chest.
A sterile liquid such as saline solution is used to fill the bottle to a level which covers the first end of the drainage tube. The sterile liquid is intended to act as a seal or one-way check valve which prevents air from moving back up through the drainage tube to the patient's chest. The bottle is also vented to atmosphere through the rubber stopper so that when the bottle is placed below the level of the patient's chest, gravity will effect drainage of fluid from the pleural cavity into the drainage bottle. Gravity drainage systems, however, tend not to work if the lung is fully collapsed. Moreover, at times there may be a major fluid leak which requires additional drainage capacity.
Another type of drainage system uses a vacuum or suction instead of relying upon gravity. Suction drainage systems typically include a water manometer which is connected to a source of suction and which controls the level of suction applied to the pleural cavity of the patient, because an uncontrolled level of suction may damage the surrounding tissue. The manometer bottle is in turn connected to a bottle which contains a water seal similar to the type of water seal used in a gravity drainage system. The bottle containing the water seal may then be also connected to a third bottle which is used as the drainage bottle for collecting the fluids that are drained from the patient's chest cavity.
One of the disadvantages experienced with the use of this type of three bottle suction drainage system is the rather complicated procedure for setting up the system and interconnecting the three bottles. Also, the system is somewhat inconvenient to use because the bottles must be rinsed, washed and sterilized before they can be used again on other patients.
A more recent system which overcomes some of the disadvantages of the three bottle suction drainage system is illustrated and described in U.S. Pat. Nos. 3,363,626 and 3,363,627. These patents describe a disposable unitary or consolidated "three bottle" apparatus constructed of plastic. Rather than using separate bottles, the apparatus replaces the bottles with separate chambers that are formed as part of a single container. The apparatus retains the basic concept of the three bottle suction drainage system because one of the chambers of the apparatus is used as a manometer, and is connected to a second chamber which is used as a water seal. The second chamber is also connected to a third chamber which is used as the drainage chamber for receiving fluids drained from the patient's chest cavity.
While the apparatus described in these patents simplifies the set up procedure of the basic three bottle suction drainage system and provides for convenient disposal of the system after each use, these apparatus remain relatively complicated in construction and expensive to manufacture and use. Moreover, like the gravity drainage system and the three bottle suction drainage system, these inventions rely upon the use of an underwater seal which is intended to prevent fluids from re-entering the patient's pleural cavity.
In practice, however, an underwater seal does not always prevent fluids from re-entering the patient's chest cavity. For example, if the patient's bronchial tubes are blocked the patient must take deeper breaths in order to expand the lungs to permit air flow around this blockage. When the patient gasps for air or continually takes these kinds of deep breaths, a sufficiently high negative pressure may be developed in the pleural cavity that the liquid used to provide the water seal may be sucked back through the drainage tube and catheter and into the pleural cavity. This obviously increases the risk of contamination to the patient, as well as hampering recovery of the patient's normal respiration. Structure for minimizing the likelihood of backflow is disclosed, for example, in U.S. Pat. No. 4,650,477 to Johnson.
Notwithstanding the foregoing, there remains a need for further improvements to the traditional water seal water manometer system. For example, it can be difficult to fill the water seal bottle of the above designs to precise levels. This is because ascertaining the liquid level in the container during fill or refill is complicated by the fact that such containers are typically positioned at inconvenient locations (e.g., at foot level or under other apparatus) in the patient's room.
Accordingly, it is an object of the present invention to provide a simplified vacuum regulator for use with a chest drainage apparatus which minimizes the risk of reverse flow of liquids from the apparatus into the patient. A further object of the present invention is to provide a vacuum regulator apparatus which can be easily filled with a precise repeatable amount of vacuum regulating liquid. Yet another object of the present invention is to provide a chest drainage apparatus which is easy to use and cost-effective to manufacture.